Leeches and lances might seem like prescriptions from the past. But bloodletting might be back in vogue. A small study shows that losing a little blood might improve cardiovascular health for obese people who also have what’s called metabolic syndrome.

The study tracked 33 patients with metabolic syndrome—defined by the presence of some of an assortment of conditions, such as high cholesterol, hypertension and insulin resistance. Researchers took 300 milliliters of blood from the patients, a little less than the one pint standard donation, with a repeat treatment a month later.